The Federal Motor Carrier Safety Administration (FMCSA) requires that an active and valid U.S. Department of Transportation (USDOT) identification number must be properly displayed on commercial motor vehicles. The USDOT's regulations mandate that companies that operate commercial vehicles transporting passengers or hauling cargo in interstate commerce must be registered with the FMCSA and must have a USDOT number. The information to be displayed on both sides of the vehicle consists of (a) the legal name or a single trade name of the motor carrier operator and (b) the operator's motor carrier identification number preceded by the letters “USDOT”. A violation of the vehicle identification requirements can result in a fine of as much as, for example, $11,000.
A number of transportation management companies are interested in automated camera-based recognition of USDOT numbers, wherein a camera is installed on the side of the road and triggered by an in-road sensor to capture an NIR/RGB image of an incoming truck. The captured image is then processed to first localize and then recognize the USDOT number on the side of the vehicle.
Currently, techniques are in operation, which automatically recognize USDOT numbers from vehicle side images captured by an NIR camera. FIG. 1, for example, illustrates a sample prior art image 10 of a side vehicle captured by a camera. The image 10 shown in FIG. 1 is a sample of the image of the side of a truck. The particular image 10 depicted in FIG. 1 not only contains the US DOT number at the bottom of the truck door, but the vehicle identification number in the center and the name of the trucking company above that. Other trucks may contain additional information such as the weight of the truck and the location of the trucking company. A full image of the truck may also contain text in the form of marketing signage and information that identifies the function of the truck. An algorithm to identify the tag number must be robust against the presence of all this additional information.
The USDOT number is written on the side of the truck either to the right of or below the “USDOT” tag. The USDOT tag and number can be written with a variety fonts and sizes on the side of the truck. The localization and recognition systems have to account for this variation in the operational phase. One approach to localize the USDOT number is to first locate the text “USDOT” preceding the USDOT number using an OCR engine. The standard approach is robust for high quality images characteristic of news and movies. However, image captures of the side of the truck are not always performed under optimal conditions. Imaging at night often requires a NIR camera. The images may be noisy and of low contrast.
A common practice to locate USDOT numbers in captured images is by using Optical Character Recognition (OCR) engines. Some images are captured under a variety of illumination conditions and can be noisy and have low contrast. OCR-based localization for these images yields low detection performance. The images are highly structured and can contain a great deal of text besides the USDOT tag number. OCR-free localization as will be described in this invention treats the text “USDOT” as a single item that is to be identified in the image.